In the related art, there is a known fluorescence endoscope apparatus with which an observation target site that is administered with a fluorescent reagent that preferentially accumulates in a diseased portion, such as cancer cells or the like, is irradiated with excitation light that excites the fluorescent reagent, generating fluorescence, and with which a fluorescence image having high luminance in the diseased portion can be obtained by capturing the generated fluorescence (for example, see Patent Literature 1). The fluorescence endoscope apparatus disclosed in Patent Literature 1 corrects changes in the fluorescence intensity in a fluorescence image, which depends on the observation distance, the observation angle, and so forth, by dividing the fluorescence image, which is based on the intensity of fluorescence generated at the observation target site irradiated with excitation light, by a reference image, which is based on the intensity of return light returning from the same observation target site irradiated with reference light.